Device for measuring a current flowing in a cable

ABSTRACT

An exemplary embodiment relates to a measuring device for measuring a current flowing in a first cable. The measuring device includes a measuring shunt in the form of a plate connected in series with the first cable and associated with a measuring electronic card connected to a data transmission cable. The measuring shunt further includes a measuring portion of resistive alloy coupled to connection portions on either side of the measuring portion. The connection portions are integrally formed with the measuring portion, and the first cable is secured to at least one of the connection portions of the measuring shunt.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application is a continuation of U.S. application Ser. No.11/793,440 filed Dec. 13, 2005, which is a is a National Stage ofInternational Application No. PCT/FR2005/003113 filed on Dec. 20, 2004,which claims the benefit of French Patent Application No. 0413593, filedDec. 20, 2004. The entire disclosure of International Application No.PCT/FR2005/003113 and French Patent Application No. 0413593 areincorporated herein by reference.

BACKGROUND

The present disclosure relates to a device for measuring a currentflowing in a cable, and more particularly to a power supply cableconnected to a battery.

Measuring devices for monitoring the load on a battery are generallyknown and might include a shunt in the form of a plate connected inseries with the cable for powering various pieces of equipment connectedto the battery, the measuring shunt being associated with a measuringelectronic card connected to a measurement data transmission cable.

Various embodiments of the above-mentioned measurement device are known.In particular, EP 1,238,288 discloses a measuring device integrated in abattery cable terminal in which the measuring shunt comprises ameasuring portion of resistive alloy associated with a measuringelectronic card, and connected to conductive connection portions alongtwo opposite edges of the measuring portion, the connection portionsboth being supported by the battery cable terminal. Such a measuringdevice is complex and difficult to make. Therefore, its cost is highcompared to the cost generally accepted for equipment of that type.

Likewise, U.S. Pat. No. 6,304,062 (Batson) discloses a current measuringdevice comprising a shunt connected between the terminals of twoadjacent battery cells. Such battery cells need to have a structure thatis specifically adapted to receive the Batson current measuring device,which results in the battery not being freely interchangeable.

An object of the disclosure is to provide a current measuring devicethat is simple in structure thereby enabling it to be made at low cost.

SUMMARY

One exemplary embodiment relates to a measuring device for measuring acurrent flowing in a first cable. The measuring device includes ameasuring shunt in the form of a plate connected in series with thefirst cable and associated with a measuring electronic card connected toa data transmission cable. The measuring shunt further includes ameasuring portion of resistive alloy coupled to connection portions oneither side of the measuring portion. The connection portions areintegrally formed with the measuring portion, and the first cable issecured to at least one of the connection portions of the measuringshunt.

Another exemplary embodiment relates to a measuring shunt. The measuringshunt is for installation between a battery cable terminal and an end ofa conductive cable and for monitoring a load on a battery. The measuringshunt includes a plate having a first connection portion and a secondconnection portion. The first connection portion is configured toconnect to the end of the conductive cable. The second connectionportion is configured to connect to the battery cable terminal. Themeasuring shunt further includes a measuring portion integrally formedfrom the plate and defined by an area between the first connectionportion and the second connection portion. The measuring portionincluding studs that extend from the measuring shunt and are configuredto be inserted into an electrical measuring circuit.

Another exemplary embodiment relates to a method of making a measuringdevice for measuring a current flowing in a cable. The method includesforming a measuring shunt from a resistive alloy, the measuring shuntcomprising a measuring portion disposed between a first connectionportion and a second connection portion. The method further includescoupling a conductive core of the cable to the first connection portionand coupling the second connection portion to a conductive material. Themethod yet further includes coupling a measuring electronic circuit tothe measuring shunt, the measuring electronic circuit being coupled to adata transmission cable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a measuring device accordingto one embodiment;

FIG. 2 is a section view on line II-II of FIG. 1 showing the measuringdevice once assembled;

FIG. 3 is a perspective view of a measuring shunt and of its connectionsaccording to another embodiment;

FIGS. 4-6 show various steps in making the shunt and its connectionsaccording to another embodiment;

FIG. 7 is a section view on line VII-VII of FIG. 6 showing the shunt andits connections once assembled.

DETAILED DESCRIPTION

Referring generally to the Figures, a measuring device for measuring acurrent flowing in a cable includes a measuring shunt connected inseries with the cable and associated with a measuring electronic cardconnected to a data transmission cable, the measuring shunt including ameasuring portion of resistive alloy connected to connection portionsmade of resistive alloy and integrally formed with the measuringportion. The power supply cable has one end secured to one face of aconnection portion of the measuring shunt. The measuring shunt can bemade by forming a plate of resistive alloy. Fastening the shunt to theend of the cable may be done in an automated manner.

Referring further to the Figures, the connection portion remote from theend of the cable is secured directly to a battery cable terminal bywelding, preferably to a conductive tab that is integral with theterminal. This makes it possible likewise to automate securing the shuntto the terminal and the resulting connection is very strong, thusenabling the measuring device to be cantilevered out from the terminalwithout damaging the device.

Other objects, features, and advantages of the present invention willbecome apparent to those skilled in the art from the following detaileddescription and accompanying drawings. It should be understood, however,that the detailed description and specific examples, while indicatingpreferred embodiments of the present invention, are given by way ofillustration and not limitation. Many modifications and changes arewithin the scope of the present invention may be made without departingfrom the spirit thereof, and the invention includes all suchmodifications.

Referring now to FIGS. 1 and 2, according to one embodiment, a measuringdevice comprises a measuring shunt 1, made from a single piece ofresistive alloy, such as manganin, and including a central portiondefined by holes 3 for forming a measuring portion 2 of measuring shunt1. On either side of measuring portion 2, measuring shunt 1 hasconnection portions 4 and 5, which in this embodiment extend parallel tomeasuring portion 2, and are offset therefrom.

Connection portion 4 is secured to an end 6 of a conductive core of acable 7 used for powering equipment. In a preferred embodiment, the end6, which is initially in the form of a bundle of conductor wires, ispressed against one face of connection portion 4 and is heated (e.g. byultrasound) so as to melt the bundle of conductor wires thereby performautogenous welding, as represented by dashed lines in FIG. 1.

Connection portion 5 is secured in the same manner (i.e. by autogenouswelding) to the face of a support tab 8, which is made of conductivematerial, such as brass. Support tab 8 is made integrally with a batterycable terminal 9. In one embodiment, support tab 8 extendsperpendicularly to axis 10 of battery cable terminal 9 in the vicinityof the base.

The measuring device also includes an electronic card 11 havingcomponents 12 which form a measuring circuit. Electronic card 11 iscoupled to measuring shunt 1 by inserting connection pins 13 into holes3 during assembly and soldering connection pins 13 therein in order tomeasure a potential difference across the ends of measuring portion 2 ofmeasuring shunt 1. Electronic card 11 is also coupled to a datatransmission cable 14.

Referring now to FIG. 2, after the measuring device components have beenassembled together as described above, a block of resin 15 is moldedaround the measuring device so as to finish off the mechanicalconnection between cable 7 and support tab 8 of battery cable terminal 9in such a manner that the measuring device is cantilevered out frombattery cable terminal 9. It should be observed that given thedisposition of the various components making up the measuring device,the total thickness of resin block 15 is less than that of battery cableterminal 9.

Referring now to FIG. 3, another embodiment is shown in which measuringshunt 16 is in the form of a bent plate having a connection portion 17with a face on which an end 6 of a conductive core of a cable 7 issecured, while a connection portion 18 remote from end 6 of cable 7 issecured to a connection tab 19 extending parallel to the axis of abattery cable terminal 39. In this embodiment, measuring shunt 16 hasstuds 20 that extend from the top edge of measuring shunt 16 to define ameasuring portion 21. Under such circumstances, an electronic card (notshown) is preferably mounted perpendicular to measuring shunt 16, byinserting studs 20 into holes in an electrical circuit carried by anelectronic card.

Referring now to FIGS. 4-6, various steps in making a measuring deviceare shown according to one embodiment. In this embodiment, the measuringshunt is in the form of a rectangular plane plate 22. The cable isstripped over a length that is slightly greater than the length ofrectangular plate 22 so as to reveal its conductive core 23 which ispressed against one of the faces of rectangular plate 22 andautogenously welded thereto by melting the conductor wires making upconductive core 23. In the stripped portion, conductive core 23 is thusin the form of a bar secured to the corresponding face of rectangularplate 22 as shown in FIG. 5. As shown in FIG. 6, conductive core 23 isthen machined (e.g. by milling) in order to eliminate the centralportion of conductive core 23 so that at the end of this operation, themeasuring shunt is secured to the ends of two cable segments 24 withtheir conducive ends 25 being spaced apart by a distance D that definesthe measuring portion of measuring shunt.

Referring now to FIG. 7, an electronic card 26 having circuit contacts27 on its bottom face is secured to conductive ends 25 of cable segments24 in order to pick up a potential difference between conducive ends 25.As before, electronic card 26 is connected to a data transmission cable28 and the assembly is embedded in a resin block 29.

The present invention is not limited to the embodiments described andvariants can be applied thereto without departing from the spirit of theinvention as defined by the claims.

In particular, the invention is not restricted to the embodiments shownof the measuring shunt in which one of the connection portions issuitable for securing directly to the side wall or to the end edge of abattery cable terminal of conventional structure.

1. A measuring device for measuring a current flowing in a first cable,the measuring device comprising: a measuring shunt in the form of aplate connected in series with the first cable and associated with ameasuring electronic card connected to a data transmission cable, themeasuring shunt comprising a measuring portion of resistive alloycoupled to connection portions on either side of the measuring portion;wherein the connection portions are integrally formed with the measuringportion, and the first cable is secured to at least one of theconnection portions of the measuring shunt.
 2. The measuring device ofclaim 1, wherein a cable end of the first cable is secured to thecorresponding connection portion by autogenous welding.
 3. The measuringdevice of claim 2, wherein a connection portion remote from the cableend is secured directly to a battery cable terminal by welding.
 4. Themeasuring device of claim 3, wherein the battery cable terminal includesa conductive tab integral with the battery cable terminal.
 5. Themeasuring device of claim 4, wherein the conductive tab extendsperpendicularly to an axis of the battery cable terminal.
 6. Themeasuring device of claim 5, having a total thickness less than batterycable terminal thickness.
 7. The measuring device of claim 1, whereinthe measuring shunt includes holes defining the measuring portion of themeasuring shunt, and the electronic card includes connection pinsconfigured to engage the holes.
 8. The measuring device of claim 1,wherein cable segment ends are secured to each of the connectionportions.
 9. A measuring shunt for installation between a battery cableterminal and an end of a conductive cable, the measuring shunt formonitoring a load on a battery, the measuring shunt comprising: a platehaving a first connection portion and a second connection portion, thefirst connection portion being configured to connect to the end of theconductive cable, the second connection portion being configured toconnect to the battery cable terminal; and a measuring portionintegrally formed from the plate and defined by an area between thefirst connection portion and the second connection portion, themeasuring portion including studs that extend from the measuring shuntand are configured to be inserted into an electrical measuring circuit.10. The measuring shunt of claim 9, wherein a block of resin is moldedaround the measuring device, a portion of the cable and a portion of thebattery cable terminal to strengthen a mechanical connection between thecable, the measuring shunt, and the battery cable terminal.
 11. Themeasuring shunt of claim 9, wherein the second connection portion isconfigured to securably engage a connection tab of a battery cableterminal, the connection tab extending parallel to the axis of thebattery cable terminal.
 12. The measuring shunt of claim 9, wherein thestuds extend from a top edge of the measuring shunt.
 13. The measuringshunt of claim 9, wherein the electrical measuring circuit is carried byan electronic card and the electronic card is mounted perpendicular tothe measuring shunt when the studs are inserted into the electricalmeasuring circuit. 14.-20. (canceled)